Dural Venous Sinuses and Meninges (fellow) Flashcards
What are the cranial meninges made of?
Three dense regular connective tissue layers that separate the soft tissue of the brain from the bones of the cranium
Encloses blood vessels to the brain
Contain and circulate CSF
Form some of the veins that drain blood from the brain
What are the layers of the scalp and meninges superficial to deep
Scalp
Skull
Periosteal Dura Mater
Meningeal Dura Mater
Arachnoid Mater
Subarachnoid Space
Pia Mater
Cerebral Cortex
Describe the Dura Mater
Composed of two layers
- Periosteal layer, attached to bone
- Meningeal layer, deep to periosteal layer
Strongest layer of the meninges
These two layers are typically fused except in specific areas where the two layers separate to form large, blood-filled spaces called dural venous sinuses.
Falx Cerebri
Dural venous septa, separating the left and right hemispheres of the cerebrum
Describe the Arachnoid Mater
- Located immediately internal to the dura mater
- The part made of collagen and elastic fibers is called the arachnoid trabeculae (spider’s web)
- Between the arachnoid and the dura mater is the subdural space
- Deep to arachnoid is subarachnoid space
Describe the Pia Mater
Innermost menix
Thin, delicate layer of CT adhering to the brain tissue, following the contours of the surface
What is the cranial dural septa
the meningeal layer of the dura mater extends as flat partitions (septa) deep into the cranial cavity at four locations called cranial dural septa
What does the dural septa function as?
partition the brain and provide support and stabilization to the whole brain
What are the four cranial dural septa?
Falx Cerebri
Tentorium Cerebelli
Falx Cerebelli
Diaphragma Sellae
What lies within the cranial dural sinuses?
Dural Venous sinuses:
- superior and inferior sagittal sinuses
- straight sinus
- sigmoid sinus
- transverse sinus
Clinical Note
Cavernous Sinus Thrombosis
Sx: high fever, periorbital edema and chemosis, cranial nerve palsies, decreased visual acuity
Dx: CT/MRI
Rx: IV Abx, heparin, surg. consult
Describe CSF
clear, colorless liquid that circulates in the ventricles and subarachnoid space
bathes surfaces of CNS and surrounds it
provides buoyancy, protection and stability
Production and compostion of CSF
formed by choroid plexus in each ventricle via ependymal cells that originate from the blood plasma
similar in composition to the blood plasma but with more Na, H, Ca and less K.
Function of the Emissary vein?
drain from scalp into sinus
Function of the bridging vein?
drain cerebral cortex into dural venous sinus
Describe the Subdural Space
“potential space”
only seen when something is wrong, like bleeding from the bridging vein into the subdural space or separation of the arachnoid+dura mater after an LP
Note that there are many important arteries in this space (ICA)
What are the cranial dural septa separating
Falx Cerebri-separates lobes of cerebrum
Diaphragma Sellae-lies over optic chiasm and pit.
Tentorium Cerebelli-separates cerebrum from cerebellum
Falx Cerebelli-separates cerebellum lobes
What is significant about the diaphragma sellae?
overlies pituitary gland and cavernous sinus
What is the arterial supply to the meninges?
Middle meningeal artery (frontal and parietal branches)
comes of Maxillary A. off of ECA out of foramen spinosum
What is the innervation of the Meninges?
V1-anterior and posterior meninges
V2- mid anterior meninges
V3- outer and middle meninges
C2-3 fibers base/bottom of meninges (floor of posterior cranial fossa)
Epidural Hematoma
middle meningeal artery
looks like a convex lens
stops in this shape due to dura adhering tightly to suture lines
Clinical Vignette: hit in side of head over Pterion (weakest) and strike middle meningeal A. Lucid interval followed by acute onset of mental status changes/deteriation
Subdural Hematoma
bridging veins
crescent shape
Clinical Vignette: potential space (subdural) is open. Old person falls or MVA (decell/accel. injury) or Shaken Baby Syndrome
common in babies or old people as veins are weaker
Subarachnoid hemorrhage
cerebral arteries
spiderweb looking shape over the circle of Willis
Clinical Vignette: “worst headache of my life” may have aura, N/V. Maye see blood on LP. RF include post-menopausal, HTN, polycystic kidney disease, Ehlers-Danlos.

Know These
The internal carotid a. and the cavernous sinus
ICA is very tortuous and contains these parts:
cerebral-goes up and becomes circle of willis
cavernous-within sinus
petrous-descends
cervical-lowest part
Hydrocephalus
When blood is in the subarachnoid space, it is unable to be filtered by the arachnoid granulatum and will cause damage and fibrosis.
This will clog the system and the CSF will accumulate and compress the brain and enlarge the ventricles causing hydrocephalus
note that the sinuses are not covered in the blood brain barrier